Compound for preventing the formation of scale, corrosion, and pitting in steam-generators.



} UNITED s'ra rns PATENT orricn.

OTTO HUGO SCI-IROEDER. OF LONDON, ENGLAND.

COMPOUND FOR PREVENTING THE FORMATION OF SCALE, CORROSION, AND FITTINGIN STEAM-GENERATORS.

Specification of Letters Patent.

Application filed October 21, 1910. Serial No. 588,270.

No Drawing.

Patented Apr. 11, 1911.

To all whom "it may concern:

Be it known that I, Orro HUoo Sermonnen, a subject of the King of GreatBritain and Ireland, residing at 27 Frith street, Shaftsbury avenue,London, WV. 6., England, chemist, have invented a New or ImprovedCompound for Preventing the Formation of Scale, Corrosion, and Pittingin Steam-Generators, of which the following is a specification.

This invention relates to a new or improved compound, for the preventionof ini-rustatiou, corrosion, and pitting, in steam generators, and thelike.

\Vhen the hydrate of barium Ba(HO,) is acted upon by an aqueous solutionof tannin, preferably a solution of tannin capable of ,ti'n'ming aglucoside, such as querci tannic acid (G 11 0,), barium tannate (BaC,,I-I,,O,,) is tormed; this barium tannate is an excellent compound forpreventing incrustation, corrosion, and pitting, in steam generators,and the like.

The incrustating properties in feed water are the salts of lime insolution, 2'. 6., the calcium carbonate (C /2100,) and the calciumsulfate (CaSOJ. W'hen barium tannate is introduced into water containingthese cal cium compounds the following reaction takes place (Calcium(Calcium (Barium carbonate.) sulfate.) tannatc.)

2CaO,,H,,(),,+BaSO,+BaC(),

(Calcium (Barium (Barium tnnnate.) sulfatm) carbonate.)

The calcium and barium compounds resulting from this reaction are notcapable of forming scale, as they fall to the bottom in a non-adherentcondition.

The barium tannate may be used either in the solid or in the liquidstate, and may be mixed with the feed water before it.enters .the steamgenerator, or it may be ted into the generator, at suitable intervals,and in "quantities dependent upon the amount of been found that watercontaining a small percentage of tannin will not corrode metal, and willalso prevent pitting.

The barium tannatc, instead of being manufactured from the bariumhydrate Ba(1IO. may also be made from the barium carbonate, or any othercompound or salt of barium which the tannin is capable of decomposing,and with the base (barium) it is able to combine, barium chloridexcepted.

In addition to the barium tannate, I may employ other substances such assodium thiosulfate, sodium phosphate, or any other suitable organic orinorganic substances, hydrochloric acid excepted, without altering thesubstance of my invention, whichisessentially the use of barium tannatefor the pre vention of the formation of scale, and corrosion, andpittin'g in steam generators.

- I am aware that it has been proposed before to use a mixture of bariumchlorid and tannic acid, which, however, does not form barium tannate asI. propose to use. There is a strong objection to the use of thismixture of barium chlorid and tannic acid, inasmuch as calcium chloridis formed with waters coi'itaining calcium salts. This calcium chloridis liable to attack boiler mountings and packings, and corrode theboiler plates and rivets. The objection is done away with by the use ofbarium taunatc as no chlorids can be formed.

lVh-at I claim as my invention and desire to secure by Letters atent isl. A compound tor preventing the formation of scale, pitting andcorrosion of steamtion of scale, pitting and corrosion of steamgenerators consisting, of a mixture of hydrate ol barium and an aqueoussolution of tannin, capable of forming a glucoside.

3. A compound for preventing the formation of scale, pitting andcorrosion of steam generators consisting of a mixture of hydrate ofbarium and an aqueous solution of tannin such as quercitannic acid.

4. A compound for preventing the formation of scale, pitting andcorrosion of steam generators consisting of a mixture of hydrate ofbarium and an aqueous solution of tannin and the admixture of freetannic signed my name to this specification in the acid. presence or twosubscrlblng witnesses.

5. A compound for preventing the formation of scale pitting andcorrosion of steam OTTO HUGO SOHROEDER' I 5 boilers consisting of bariumtannate and free Witnesses:

tannic acid. LIONEL ERNEST BUssnY,

In testimony whereof I hgye hereunto ROBERT OWEN HUGHES.

